In recent years, a door configured to open and close a car doorway of an elevator includes a safety device. The safety device detects, during a door closing operation of a car door, that an obstacle such as a user of the elevator or baggage of the user is brought into contact with a leading end portion of the car door, and reverses the car door and a landing door in a door opening direction before the caught of the obstacle by the car door.
As such a safety device, for example, there is known a safety shoe. The safety shoe is provided on a side surface of the car door on the landing side so that a part thereof is protruded from the leading end portion of the car door. Further, the safety shoe is provided vertically between upper and lower sides of the car door. When the safety shoe is moved by a distance set in advance in the door opening direction of the car door due to an obstacle or other reasons, a shoe switch detects an amount of movement of the safety shoe. Then, when the amount of movement exceeds a threshold value, the car door and the landing door are reversed.
However, in some cases, operation failure occurs in the shoe switch. For example, although no obstacle is in contact with the safety shoe, the safety shoe may be erroneously detected as being moved, and the reversing operation of the car door and the landing door may be repeated. Such operation failure is hereinafter referred to as “ON failure”.
Further, in contrast, when the movement of the safety shoe is not detected even though an obstacle is in contact with the safety shoe, the car door and the landing door do not perform the reversing operation. In this case, a trouble that the obstacle is caught in the door may occur. Such operation failure is hereinafter referred to as “OFF failure”.
As related-art failure detection devices configured to detect the failure of the safety device, there are known, for example, Patent Literatures 1 to 3.
In Patent Literature 1, there is described a method of detecting ON failure. In Patent Literature 1, the shoe switch configured to detect the amount of movement of the safety shoe is formed of normally closed contacts. Therefore, when a door opening button is not pressed and a door closing command is ON while the door is fully opened, in a normal state, the shoe switch is closed. Meanwhile, when the shoe switch is opened, it is determined that the safety shoe has the ON failure.
Further, in Patent Literature 2, there is described a method of detecting OFF failure. In Patent Literature 2, a protruding portion is mounted on the safety shoe. The protruding portion is provided so as to be opposed to a doorstop portion of the car door. During normal operation, the protruding portion moves the safety shoe while the door is fully closed, and then the inner contacts of the shoe switch are opened. Therefore, when the inner contacts of the shoe switch are still in the closed state even while the door is fully closed, it is determined that the safety shoe has the OFF failure.
Further, in Patent Literature 3, there is proposed a method involving providing an electromagnet device for retreating the safety shoe, and causing the safety shoe to retreat during the door closing operation through control of the electromagnet device to detect the operation failure of the safety shoe. In Patent Literature 3, the electromagnet device is used to turn on or off the shoe switch at any timing.